A motor drive may be a large and expensive piece of equipment such as a turbo-electric motor for a locomotive. An accessory driven by the drive is generally smaller and less expensive. In the event that the accessory locks up so that its shaft is non-rotatable, it is necessary to utilize a coupling which will interrupt the connection between the drive and the accessory. Heretofore, such interruption has been attained by using a coupling having a shear pin whereby the drive and accessory are sill coupled together but in a non-driving relationship. See U.S. Pat. Nos. 1,414,207 and 3,359,171.
Another prior art patent which shows a device for disconnecting a jet engine from one of its accessories is U.S. Pat. No. 3,220,218. The subject matter is this patent is a complex device in which a spring-loaded mechanism is operated to stop the rotation of a nut with a shaft. As a result, the nut moves up the shaft until it engages a flange or shoulder. This in turn results in a fracture of the shaft to effect a disconnection.
The present invention solves the problem of providing a coupling which will completely disconnect the drive for the accessory without fracturing any of the components except for a shear pin and accomplishes the same in a manner which is simple and inexpensive.